The invention relates to motor vehicles in general, and more particularly to improvements in power trains for use in motor vehicles. Still more particularly, the invention relates to improvements in arrangements for actuating or operating automated torque transmitting systems (such as friction clutches or hydrokinetic torque converters with lockup or bypass clutches) and/or automated transmissions (hereinafter called gearboxes) in the power trains of motor vehicles.
It is known to operate or actuate an automated gearbox or an automated clutch by a control unit which receives signals from one or more sensors, electronic circuits and/or other monitoring means and transmits signals to one or more actuators which directly actuate or operate a gearbox to select a particular gear ratio and/or to shift into a selected gear ratio; the same actuator or additional actuator(s) can be utilized as a means for automatically selecting the. torque to be transmitted by an automated clutch or another automated torque transmitting system between a prime mover (such as an internal combustion engine or a hybrid prime mover in a motor vehicle) and the input element of a gearbox in the power train of a motor vehicle. The connection between one or more actuators and the actuated part(s) of a gearbox and/or a clutch can include one or more driving units. For example, the means for actuating or operating an automated gearbox can comprise a control unit (such as a computerized electronic circuit), a first actuator which operates a gear ratio selecting component of the gearbox by way of a first driving unit, and a second actuator which operates or actuates, by way of a second driving unit, a component which shifts the gearbox into a selected ratio. One and the same component of the automated gearbox can be used to first select a given gear ratio and to thereupon shift the gearbox into the thus selected gear ratio.
An actuator of the above outlined character can be a hydraulically operated actuator. A drawback of such clutch or gearbox actuating means is that the hydraulically operated actuator or actuators occupy much space and comprise a large number of parts. This contributes to the cost and bulk of the clutch and/or gearbox, to the cost and bulk of the actuating means for the clutch and/or gearbox, and to the cost and bulk of the entire power train. As a rule, hydraulically operated actuator comprise accumulators for pressurized fluids, numerous valves, numerous conduits, several cylinder and piston assemblies and/or other components or constituents.
Another drawback of heretofore known power trains which comprise automated torque transmitting systems and/or automated gearboxes is that the sensors which they employ to monitor the speed, acceleration, distances covered and/or other parameters which are to be considered for automatic shifting of a gearbox and/or for automatic selection of torque to be transmitted by an automated clutch are too bulky and/or unreliable and/or insufficiently sensitive for utilization in such power trains.